public class demo {
    public static void main1(String[] args) {
        StringBuilder stringBuilder =new StringBuilder("yuiggky");
        stringBuilder.append("hekkas");//拼接
        System.out.println(stringBuilder);
    }


    public static void main(String[] args) {
        int[] array = null;
        System.out.println(array[100]);
        //System.out.println(10/0);算数异常
        System.out.println("after");
    }
}
